The objective of this project is to study monocyte-lymphocyte interactions in patients with mycosis fungoides to better understand the pathogenesis of this disease and as a model for cellular cooperation in other malignant diseases and in normal individuals. Cellular interaction will be measured in mixed leukocyte reactions, mitogen-induced antibody production and blastogenic responses, co-stimulator assays, and monocyte and lymphocyte chemotaxis experiments. Cells will be fractionated by standard density and adherence techniques and also by counterflow centrifuge separation (elutriation) to carefully distinguish contributions by monocytes and lymphocytes. Tissue transudates from MF lesions will be tested in vitro for effects on cellular stimulation, and on cellular movement.